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Astronomy
Earth Science, Chapter 4
5th Grade
Nazareth Intermediate School
What is known about stars?
I. The Sun
A. At the center of our universe
1.
Average brightness, looks the brightest to us because
it is closer to the Earth than any other star
B. Hot ball of glowing gases
What is known about stars?
What is the sun made of?
The sun is a huge, glowing sphere of hot gas. Most of this gas is
hydrogen (about 70%) and helium (about 28%). Carbon,
nitrogen and oxygen make up 1.5% and the other 0.5% is
made up of small amounts of many other elements such as
neon, iron, silicon, magnesium and sulfur. The sun shines
because it is burning hydrogen into helium in its extremely
hot core. This means that as time goes on, the sun has less
hydrogen and more helium.
What is known about stars?
C. Nuclear reactions within the sun create large
amounts of heat and energy
1. Immense amount of heat causes the Sun to
glow
D. Our sun is yellow
1. Stars also come in white, blue, and red
2. Some are dark and do NOT glow
Why do you think stars are different colors?
What is known about stars?
E. Parts of the Sun
Structure of
the Sun Video
What is known about stars?
E. Parts of the sun
1. Convection Zone – currents of hot gases carry energy
as they rise to the surface and then fall
2. Radiation Zone – where hydrogen atoms combine to
create helium (nuclear fusion)
3. Photosphere – surface of the sun
4. Chromosphere – lower layer of sun’s atmosphere
5. Corona – outer layer of the sun’s atmosphere, reaches
millions of km into space
Corona ->
What is known about stars?
II. Distances in Space
A. Scientists use kilometers on Earth to
measure distance
B. Astronomical Units (AU) measure distances
between planets
C. Neither are big enough to measure outside
of our solar system, scientists use a unit based
on the speed of light
What is known about stars?
1. This is called light years
2. In one year light travels as far as
9,500,000,000,000 kilometers
Write this number in word-form.
3. used to measure distance in space
What is known about stars?
D. Closest star to Earth (other than sun) –
Proxima Centauri
1. It takes 4.3 years for light from this star to
reach Earth
E. Some stars are much further away
1. Cassiopeia A is 11,000 light years away
F. It takes 8 minutes for light from our sun to
reach the Earth
What is known about stars?
Why is looking at the stars like looking back in
time?
What is known about stars?
III. The Properties of Stars
A. Stars are grouped by brightness, color, and
size
1. brightness and color can depend on the
temperature of the star
What is known about stars?
B. Star’s brightness depends on how big it is,
how hot it is, and how far away from Earth it is
1. The bigger and hotter it is, the more light it
gives off
2. The proximity to Earth affects how bright it
is to people
Why does proximity affect brightness?
What is known about stars?
C. The color of the sun is determined by
temperature
Coolest
Hottest
red -> orange -> yellow -> white -> blue-white
What is known about stars?
D. Size of stars
1. smallest can be smaller than Earth
Make a predictiction, how many times greater is
the diameter of the largest known star?
Size of Stars video
What is known about stars?
2. The largest known star is VV Cephei
a. 2,644,800,000 km in diameter
b. 1900 times the diameter of our Sun
c. 649,800 times the diameter of Earth
3. Polaris, “North Star”, varies in size
How can a star vary in size from day to day?
What is known about stars?
Polaris is
actually a
group of
3 stars which
move around
each other in
space.
What is known about stars?
IV. Constellations and Galaxies
A. Constellation – stars that seem to be in a
group
List at least 3 constellations which you have
heard of before
What is known about stars?
2. People in ancient times made up stories
about constellations and how they got up in
the sky
What is known about stars?
3. From Earth the constellations look like groups,
really they are NOT near each other
Star Charts
• A star chart is a map of the night that enables
you to locate stars, celestial bodies, other
planets and different patters of stars called
constellations.
• When using a star chart be sure that you have
a correct map in accordance with your
location and date. Generally star charts are
different for Northern and Southern
hemispheres.
Star Charts
To use the Star Chart, find the
date. The correct date needs
to be on the bottom. Put the
chart over your head and
locate the stars.